Test V4 tx. with Sapling outputs but no spends

Find a transaction V4 vector that has Sapling outputs but no spends, and
check that the verifier accepts it.

zebra-consensus/src/transaction/tests.rs

@@ -704,16 +704,53 @@ async fn v4_with_sapling_spends() {
     zebra_test::init();
     zebra_test::RUNTIME.block_on(async {
         let network = Network::Mainnet;
-        let blocks = zebra_test::vectors::MAINNET_BLOCKS.iter();
 
+        let (height, transaction) = test_transactions(network)
+            .rev()
+            .filter(|(_, transaction)| {
+                !transaction.is_coinbase() && transaction.inputs().is_empty()
+            })
+            .find(|(_, transaction)| transaction.sapling_spends_per_anchor().next().is_some())
+            .expect("No transaction found with Sapling spends");
+
+        let expected_hash = transaction.hash();
+
+        // Initialize the verifier
+        let state_service =
+            service_fn(|_| async { unreachable!("State service should not be called") });
+        let script_verifier = script::Verifier::new(state_service);
+        let verifier = Verifier::new(network, script_verifier);
+
+        // Test the transaction verifier
+        let result = verifier
+            .clone()
+            .oneshot(Request::Block {
+                transaction,
+                known_utxos: Arc::new(HashMap::new()),
+                height,
+            })
+            .await;
+
+        assert_eq!(result, Ok(expected_hash));
+    });
+}
+
+/// Test if a V4 transaction with Sapling outputs but no spends is accepted by the verifier.
+#[tokio::test]
+async fn v4_with_sapling_outputs_and_no_spends() {
+    zebra_test::init();
+    zebra_test::RUNTIME.block_on(async {
         let network = Network::Mainnet;
 
         let (height, transaction) = test_transactions(network)
             .rev()
             .filter(|(_, transaction)| {
                 !transaction.is_coinbase() && transaction.inputs().is_empty()
             })
-            .find(|(_, transaction)| transaction.sapling_spends_per_anchor().next().is_some())
+            .find(|(_, transaction)| {
+                transaction.sapling_spends_per_anchor().next().is_none()
+                    && transaction.sapling_outputs().next().is_some()
+            })
             .expect("No transaction found with Sapling spends");
 
         let expected_hash = transaction.hash();